Improvement in valve-gears for direct-acting steam-engines



UNITED STATESy PATENT QFFICE.,

JOHN TESSEYMAN AND EDMHND I.` HOWARD, OF DAYTON, OHIO.

IMPROVEMENT lN VALVE-GEAR'S FOR DIREClACTING STlEAM-ENGlNl-IS.V

Specification forming part of Letters Patent No. 139,439, dated May 27, 1873; application tiled January 4, 1873.

To all whom it may concern:

Be it known that we, JOHN TEssEYMAN and E. I. HOWARD, of Dayton, in the county of Montgomery and in the State of Ohio, have invented certain new and useful Improvements in Valve-Gear for Direct-Acting Steam-Engines; and do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawing making a part of this specification, in Which- Figure lis a side elevation of a pumpingengine containing our improvements. Fig. 2 is a plan view of the upper side of the same; and Figs. 3 and 4 are side elevations of modifications of the construction of the reciprocating i head used for operating the valve.

Letters of like name and kind refer to like parts in each of the gures.

The design of our invention is to increase the efficiency, economy, and durability of direct-acting engines, to which end it consists, principally, in the employment of a reciprocating cross-head provided within one of its vertical sides with two substantially horizontal grooves which are connected at their ends,

and diverge vertically at their centers to a distance equal to the throw of the valve, and, through suitable mechanism, impart motion to said valve, substantially as and for the purpose hereinafter specified. It consists, fur-l ther, in the employment of a spring cut-off at each end of the intersecting grooves for the purpose of changing the course of the wristpin, or other device that travels therein, substantially as is herein after shown. It consists, iinally, in the device as a whole, when constructed to operate substantially as and for the purpose' hereinafter set forth.

Although applicable to all classes of directacting engines, for convenience, its use upon lower end contained within a corresponding groove, F, that is formed within the bed-plate (l, and which serves as a guide for said head.l Upon one side of the head E is a plate, G,V

within the outer vertical face of which are cut two grooves, H, that are formed upon circular lines and at their ends intersect so as tohave l `in plan view a double-convex form.

sides hof the grooves H are made separate from said plate and are pivoted near the 1ongitudinal center of the latter so as to permit their outer ends tobe moved inward and close the corresponding portions of saidgroove, as shown. A spring, I, secured at one end to or upon the edge of the plate, and at its other end bearing upon the free end .of each pivoted cuto h, presses the latter inward against the inner side of its groove. The steam-chest B is, preferably, placed upon the side of its`cylinder, which corresponds to the position of the plate G, and the valve-stem K, extending horizontally forward, is pivoted to or upon a vertical arm, L, of a rock-shaft which rests within a standard, M, that extends upward from the' bed-plate C. The inner'arm Lof the rockshaft extends horizontally forward toa point midway between the cylinders A and B, and at its end is provided with awrist-pin, Z, that eX- tends laterally inward and fits into the grooves H. As thus arranged, the reciprocating movementofthe cross-head E will cause the wrist-pin L to follow alternately the course ofthe upper and lower grooves H, the springs I operating through the pivoted cut-offs h, to press said pin from one groove into the other as it reaches the ends of the same, by which means the vertical motion thus imparted to said pin and the end of the arm L' and communicated through the arm L and valve-rod K to the valve, will cause the latter to change the course of steam to and from the ends of the cylinder B, in the usual manner. As constructed, the grooves will give to the valve substantially the same motion as would be obtained by use of an ordinary eccentric, andenable the steam to be used expansively, so as to cause the piston to have a low rate of speed at either end of its stroke and a high rate at the central portion thereof, instead, asis usually the case, of having the speed of the piston continue to or near the limit of motion and .then suddenly checked and said piston thrown backward withrashock. Although the form of groove shown is, preferably, employed, it will be seen that the same may be varied so as to give any desired motion to the valve. As illustrations of such modifications, Fig. 3 shows grooves arranged so as to cause a full head of steam to be' carried to nearly the end of the stroke, when the valve will be suddenly changed and steam thrown upon the opposite side of the piston, the motion produced being similar to that found in most pumping-engines. Fig. 4 shows such an arrangement of grooves as to cause the supply of steam to be shut oft' at one-half stroke, from whence to near the termination of said stroke the steam is used expansively, after which the valve is chan ged either quickly, as seen by the full lines, or more slowly, as indicated by the dotted lines. v l

The especial advantages obtained by this improvement are, rst, any desired motion may be given to the valve, which motion in stead of being constant in either direction, may be variable to any degree and in any manner; second, the valve-gearing is more simple in construction, costs less, and requires less skill to operate than those commonly used.

I, substantially as and for the purpose shown.

3. The valve-gearing described, as a whole, consisting of the reciprocating crosshead E, provided withthe groove H, the rockshait L and n', and the valve-rod K, when said parts a j constructed and combined, substantially as and for the purpose set forth.

In testimony that We claim the foregoing we have hereunto set our hands this 21st day of December, 1872.

JOHN TESSEYMAN. EDMUND I. HOWARD.n

l/Vitnesses:

C. D. IDDINGs, THOMAS OLEGG. 

